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Of public wifi networks and DNS servers

SteevLSteevL What can I do for you?Registered User regular
edited April 2010 in Help / Advice Forum
I work in a public library and we offer free wifi. The way it is supposed to work is pretty simple: a patron brings in their laptop, they connect to our access point, and then open up an internet browser. Once they agree to the terms of service -- always the first thing to appear in the browser -- it'll take them to their default homepage.

It works pretty well for the most part, but occasionally I'll have a patron approach me and say they cannot connect to the internet. Usually they're on Windows Vista or 7. Up until recently, I couldn't figure out why, and our IT people aren't really allowed to touch the public's private laptops for legal reasons. What was weirder is that they said they had no problems connecting to wifi anywhere else, be it Starbucks, McDonald's, home internet, etc.

Anyway, I figured out that usually the problem was in their wireless connection properties, under Internet Protocal Version 4 properties, they would usually have it set to use a specific DNS server. Once I had them click on "Obtain a DNS server automatically" they had no further problems with our wifi. However, since I don't know very much at all about networking, I really don't know how this will affect their ability to connect to other networks. In the few cases where I've done this, I made them write down the specific DNS server address and showed them where to type it in if they have problems outside the library.

So basically, my question is am I screwing up their connection at all? This is pretty advanced stuff for the average person coming into the library and I don't really feel comfortable making these changes, so I rarely do it.

SteevL on


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    DjeetDjeet Registered User regular
    edited April 2010
    If their static DNS entry works other places but not at the library then other places have a firewall policy that allows DNS client requests outbound whereas the library does not (most likely your firewall only permits your internal DNS servers to do outbound DNS client requests, and the policy is that your wifi clients need to goto your internal DNS servers who will find out DNS on their behalf).

    You aren't screwing up their connection, but you should continue to show them how to note their static DNS server entries and how to set them so they can revert the setting once they leave the library. They (or whomever setup their machines) likely have reasons to use a particular DNS server.

    Djeet on
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    PirateJonPirateJon Registered User regular
    edited April 2010
    You're fine. DHCP that doesn't also hand out DNS is fucking rare.

    I mean yeah, you can setup OpenDNS or something and that will work most places, but whatever.

    PirateJon on
    all perfectionists are mediocre in their own eyes
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    bowenbowen How you doin'? Registered User regular
    edited April 2010
    Not really, having a predefined DNS can be problematic with certain connections anyways. You never know how it's set up locally. Especially if you're a roaming user.

    bowen on
    not a doctor, not a lawyer, examples I use may not be fully researched so don't take out of context plz, don't @ me
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    SteevLSteevL What can I do for you? Registered User regular
    edited April 2010
    Thanks guys! And just as I was typing this, one of the people I had helped a few weeks ago approached me and wanted to let me know she hasn't had any problems with using her laptop anywhere else.

    SteevL on
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    LegionnairedLegionnaired Registered User regular
    edited April 2010
    You can probably set up your router/firewall so all port 53 (dns) requests get shunted off to your local router automagically.

    Legionnaired on
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